1. Field of the Invention
This invention relates to extracts from peanuts hulls and pecan pith, processes for such extraction, the use of the extract for the preparation of phenolic-type resins, and the use of such resins in adhesives and as bonding agents for wood laminates, particle board, and the like.
2. Description of Prior Art
For many years agricultural residues, such as tree bark, sawdust, peanut hulls, and pecan pith, were regarded as waste products to be disposed of as cheaply as possible. However, in this era of material shortages and ecological awareness, increasing efforts have been directed away from mere disposal and toward positive utilization of such residues. Although most of such residues are still disposed of by burning or dumping, increasingly stringent air and water pollution regulations coupled with the high potential value they may have as raw materials suggests that maximum utilization of the residues is a necessity.
The use of various tree barks, especially pine, oak and redwood, and other residues, such as oat hulls, walnut shells, wood flour, and coniferous strobiles, as extenders or fillers for phenol-aldehyde resins is well known. It is also known to make alkali extracts of various tree barks and to use such alkali extracts in phenol-aldehyde resin production.
There has, however, been no disclosure of the production of alkali extracts of peanut hulls or pecan piths or the use of such extracts as a partial or complete substitute for phenol in phenol-aldehyde condensation under alkaline conditions.
Relevant prior art of which the applicant is aware is as follows:
U.S. Pat. No. 1,078,893 relates to extracting tannin from pecan shells and pith. The disclosed process consists of comminuting pecan shells and pith, mixing them with boiling water, and extraction by percolation. There is no disclosure of the use of an alkaline solution.
U.S. Pat. No. 2,574,784 relates to a phenolic resin adhesive composition containing a comminuted bark extender.
U.S. Pat. No. 2,574,785 relates to a process for treating vegetable shell material for use as a constituent of phenol-aldehyde adhesive compositions. The vegetable shell materials specifically disclosed are nut shells, such as walnut, filbert and hickory, the endocarps (stones) of drupes, such as apricot, peach and prune, and the barks of trees.
U.S. Pat. No. 2,675,336 discloses a phenolic resin especially adapted for use in the manufacture of plywood which is the reaction product of phenol, alkaline redwood bark extract, and formaldehyde. The use of more than 50% alkali soluble redwood bark extract by weight in the phenolic component is disclosed as resulting in resins of substantially reduced reactivity. Wood flower, walnut shell flour, and pulverized oat hulls are disclosed as fillers.
U.S. Pat. No. 2,773,847 discloses the reaction of tree bark fractions with an alkaline compound which is then further reacted with an aldehyde to form a resin. It is disclosed that bark fractions comprising less than about 68% cork prove to be unsatisfactory as the principal ingredients in a caustic-formaldehyde bark adhesive.
U.S. Pat. No. 2,781,286 relates to phenolic resin glue compositions containing extenders, which are finely divided modified vegetable shell materials containing certain alkali derivatives. Vegetable shell materials disclosed are the endocarps of drupes, which include shells of nuts, such as walnut, hickory, palm and filbert, pit shells of fruits, such as peach, prune and apricot, the hulls of grains and seeds, such as oat hulls, and the cones or strobiles of coniferous trees.
U.S. Pat. No. 2,782,241 relates to the digestion of coniferous barks in an aqueous alkaline solution so as to convert part of the water-insoluble portion of the bark to a water-soluble alkali derivative.
U.S. Pat. No. 2,819,295 is similar to U.S. Pat. No. 2,782,241 but relates to a different fraction of the organic chemicals of the bark and is further characterized by retained or combined nitrogen.
U.S. Pat. No. 2,823,223 relates to an approved process for the production of chemical derivatives from coniferous barks by digestion in an aqueous ammonia solution.
U.S. Pat. No. 2,831,022 relates to sodium sulfonate or sulfonic acid derivatives of polymeric phenolic materials occurring in bark and the use of such compositions as chemical intermediates and well drilling additives.
U.S. Pat. No. 3,008,907 relates to an extender for phenolic resins which is an alkali metal reaction product of a conjointly cooked alkaline mixture of a cereal flour and a vegetable material which may be ligno-cellulose. The disclosed cereal flour is wheat flour. The disclosed ligno-cellulose materials are tree bark, nut shells, and the endocarps of drupes.
U.S. Pat. No. 3,017,303 relates to extenders for phenolic resin adhesives which are naturally occurring ligno-cellulose and alkali lignin.
U.S. Pat. No. 3,025,250 relates to phenolic resins which are further reacted with alkali-bark derivatives obtained by treating suitable bark at a temperature of from about 90.degree. to 170.degree. C. with an aqueous alkaline solution.
U.S. Pat. No. 3,053,784 relates to resins derived from a sodium salt of a polymethylol phenol and a sodium substituted bark derivative. It is one of the important aspects of this invention that free formaldehyde is neither present in nor added to the composition.
U.S. Pat. No. 3,093,605 relates to extenders for plywood adhesive solutions composed of a vegetable shell flour extender and minor amounts of an at least partially oxidized extracted lignin and a non-fibrous degradation product of a vegetable shell material.
U.S. Pat. No. 3,093,607 is closely related to U.S. Pat. No. 3,093,605.
U.S. Pat. No. 3,099,633 is closely related to U.S. Pat. No. 3,093,605.
U.S. Pat. No. 3,213,045 relates to phenolic resin adhesives formulated with redwood bark dust resin extenders.
U.S. Pat. No. 3,223,667 discloses a resin composition comprising an alkali-bark derivative and a polymethylol phenolic compound which will polymerize to a phenolic resin and will also condense with the alkali-bark derivative.
U.S. Pat. No. 3,232,897 relates to resorcinol-formaldehyde cold setting adhesive resins incorporating alkali-bark derivatives as an extender.
U.S. Pat. No. 3,268,460 relates to condensing phenol and aldehyde to make a resinous condensate and then further condensing said resin with bark flour.
U.S. Pat. No. 2,293,200 relates to phenol resins containing, as an extender, a water-insoluble, finely-divided humin material obtained from the manufacture of levunic acid by acid hydrolysis of ligno-cellulose.
U.S. Pat. No. 3,328,322 relates to thermosetting molding materials comprising a phenol-aldehyde resin and an alkali-extracted douglas fir bark fiber.
U.S. Pat. No. 3,371,054 relates to alkali-bark derivatives produced by treating bark with an alkali metal hydroxide in strong aqueous solution which is heated sufficiently to carry the batch to a substantially dry state while in a non-oxidizing atmosphere, to form an alkali bark. The alkali bark may be acidified to form an acid bark. Either the acid bark or the alkali bark may be reacted with formaldehyde to form novolak-type or resole-type resins.
U.S. Pat. No. 3,389,101 relates to a resin adhesive for use in the manufacture of plywood which is formulated from a redwood extract composed of phenolics which are solvent-extracted from redwood, and phenol co-reacted with formaldehyde in the presence of an alkali hydroxide catalyst.
U.S. Pat. No. 3,429,770 relates to an extender for plywood glue compositions.
U.S. Pat. No. 3,518,210 discloses an infusable resin formed by reaction of a phenol-aldehyde condensation product with an alkali-bark derivative.
U.S. Pat. No. 3,654,200 relates to a liquid coniferous tree bark alkali which is reacted with a dimethylol amide of a dibasic acid and used as a substitute for up to 65% of phenolformaldehyde in adhesive resin formulae.
U.S. Pat. No. 3,931,071 relates to lignin sulfonate-phenol formaldehyde glue systems for particle board, hardboard and plywood.
Japanese laid-open patent application 50/34054 discloses the use of peanut hulls as an extender in phenol-formaldehyde resin adhesives for use in plywood manufacture.
Relevant literature includes the following.
Kottwitz and Forman, Sodium Palconate, Industrial and Engineering Chemistry, Volume 40, No. 12, (1948), pages 2443-2450. This article discloses the production of powdered sodium palconate by alkaline extraction of redwood bark dust followed by concentration and spray drying of the extract. The alkali-soluble material was disclosed as consisting mainly of a partially methylated phenolic acid containing aliphatic hydroxyls, phenolic hydroxyls, and carboxyl groups, in the ratio of 2:4:3.
Kulvik, Chestnut Wood Tannin Extract in Plywood Adhesives, Adhesives Age, March (1976), pages 19-21. This discloses a phenol-formaldehyde resin in which up to 50% of the phenol is replaced by a chestnut wood tannin extract added prior to the reaction with formaldehyde.
Kulvik, Chestnut, Tannin Extract as Cure Accelerator for Phenol-Formaldehyde Wood Adhesives, Adhesives Age, March (1977), pages 33-34. Chestnut wood tannin extract is disclosed as replacing resorcinol and/or paraformaldehyde as an accelerator for the cure of alkaline phenol-formaldehyde adhesive resins and has an accelerating effect on the cure of phenolic adhesives for plywood manufacture.
Saayman and Brown, Wattle-Base Tannin-Starch Adhesives for Corrugated Containers, Forest Products Journal, Volume 27, No. 4, April (1977), pages 21-25. Polyphenolic bark tannin is disclosed as a substitute for resorcinol in the production of moisture-resistant corrugated board. The bark tannins of the wattle tree are stated to resemble resorcinol more closely than phenol.
Herrick and Bock, Thermosetting Exterior-Plywood Type Adhesives from Bark Extracts, Forest Products Journal, Volume 8, No. 10, (1958), pages 269-274.
McLean and Gardner, Bark Extracts in Adhesives, Pulp and Paper Magazine of Canada, Volume 53, August (1952), pages 111-114.
Abe, Studies on the Lignin-Formaldehyde Resin, Hokkaido Forest Products Research Institute Research Report No. 55, (1970), pages 1-131.
Hall, Leonard and Nicholls, Bonding Particle Board With Bark Extracts, Forest Products Journal, Volume 10, No. 5, (1960), pages 263-272.
Chen and Rice, Veneer and Assembly Condition Effects on Bond Quality in Southern Pine Plywood, Forest Products Journal, Volume 23, No. 10, (1973), pages 46-49.
In addition to the above, the inventor presented a paper at the thirtieth annual meeting of the Forest Products Research Society held in Toronto, Canada, on July 13, 1976, entitled "Studies On The Use of Bark and Agricultural Residue Components In Phenolic Resins and Glue Mixes--Part I--Relative Activity Of Bark and Residue Extractives Toward Formaldehyde". This paper disclosed the extraction of phenol-like compounds from southern pine bark, oak bark, pecan nut pith, and peanut hulls. Various extraction means were disclosed including aqueous sodium hydroxide extraction, sulfite pulping method extraction, and hydrolysis by means of the "Hokkaido Process" to produce lignin-like compounds. Some, but not all, of the extracted components reacted rigorously with formaldehyde.